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In [[mathematics]], the '''large sieve''' is a method (or family of methods and related ideas) in [[analytic number theory]]. | |||
Its name comes from its original application: given a set <math>S\subset \{1,\cdots,N\}</math> such that the elements of ''S'' are forbidden to lie in a set ''A<sub>p</sub>'' ⊂ '''Z'''/''p'' '''Z''' modulo every prime ''p'', how large can ''S'' be? Here ''A<sub>p</sub>'' is thought of as being large, i.e., at least as large as a constant times ''p''; if this is not the case, we speak of a ''small sieve''. (The term "sieve" is seen as alluding to, say, sifting ore for gold: we "sift out" the integers falling in one of the forbidden congruence classes modulo ''p'', and ask ourselves how much is left at the end.) | |||
== Development == | |||
Large-sieve methods have been developed enough that they are applicable to small-sieve situations as well. By now, something is seen as related to the large sieve not necessarily in terms of whether it related to the kind situation outlined above, but, rather, if it involves one of the two methods of proof traditionally used to yield a large-sieve result: | |||
* '''An approximate Plancherel inequality'''. If a set 'S' is ill-distributed modulo ''p'' (by virtue, for example, of being excluded from the congruence classes ''A<sub>p</sub>'') then the Fourier coefficients <math>\widehat{f_p}(a)</math> of the characteristic function ''f<sub>p</sub>'' of the set ''S'' mod ''p'' are in average large. These coefficients can be lifted to values <math>\widehat{f}(a/p)</math> of the Fourier transform <math>\widehat{f}</math> of the characteristic function ''f'' of the set ''S'' (i.e., <math>\widehat{f}(a/p)=\widehat{f_p}(a)</math>). By bounding derivatives, we can see that <math>\widehat{f}(x)</math> must be large, on average, for all ''x'' near rational numbers of the form ''a/p''. ''Large'' here means "a relatively large constant times ''|S|''". Since <math>|f|_2 = \sqrt{|S|}</math>, we get a contradiction with the Plancherel identity <math>|\widehat{f}|_2=|f|_2</math> unless ''|S|'' is small. (In practice, to optimise bounds, people nowadays modify the Plancherel identity into an equality rather than bound derivatives as above.) | |||
* '''The duality principle'''. One can prove a strong large-sieve result easily by noting the following basic fact from functional analysis: the norm of a linear operator (i.e., <math>\sup_v |Av|_W/|v|_V</math>, where ''A'' is an operator from a linear space ''V'' to a linear space ''W'') equals the norm of its adjoint (i.e., <math>\sup_w |A^* w|^*_V/|w|^*_W</math>). This principle itself has come to acquire the name "large sieve" in some of the mathematical literature. | |||
It is also possible to derive the large sieve from majorants in the style of Selberg (see Selberg, ''Collected Works'', vol II, Lectures on sieves). | |||
== History == | |||
The early history of the large sieve traces back to work of [[Yuri Linnik | Yu. B. Linnik]], in 1941, working on the problem of the [[least quadratic non-residue]]. Subsequently [[Alfréd Rényi]] worked on it, using probability methods. It was only two decades later, after quite a number of contributions by others, that the large sieve was formulated in a way that was more definitive. This happened in the early 1960s, in independent work of [[Klaus Roth]] and [[Enrico Bombieri]]. It is also around that time that the connection with the duality principle became better understood. | |||
==See also== | |||
*[[Bombieri–Vinogradov theorem]] | |||
==References== | |||
*{{Springer|id=l/l057580}} | |||
* {{cite book | first1=Alina Carmen | last1=Cojocaru | first2=M. Ram | last2=Murty | author2-link=M. Ram Murty | title=An introduction to sieve methods and their applications | series=London Mathematical Society Student Texts | volume=66 | publisher=[[Cambridge University Press]] | isbn=0-521-61275-6 | zbl=1121.11063 | pages=135–155 }} | |||
* {{cite book | first=Harold | last=Davenport | authorlink=Harold Davenport | title=Multiplicative Number Theory | edition=3rd | others=Revised and with a preface by Hugh L. Montgomery | series=[[Graduate Texts in Mathematics]] | volume=74 | publisher=[[Springer Science+Business Media|Springer-Verlag]] | year=2000 | isbn=0-387-95097-4 | zbl=1002.11001 }} | |||
* {{cite book | first1=John | last1=Friedlander | author1-link=John Friedlander | first2=Henryk | last2=Iwaniec | author2-link=Henryk Iwaniec | title=Opera de Cribro | publisher=AMS Colloquium Publications| year=2010 | isbn=978-0-8218-4970-5 | zbl=1226.11099 }} | |||
* {{cite book | first=Christopher | last=Hooley | authorlink=Christopher Hooley | title=Applications of sieve methods to the theory of numbers | publisher=Cambridge University Press | date=1976 | isbn=0-521-20915-3 | pages=17–20 }} | |||
* {{cite book | first=Emmanuel | last=Kowalski | title=The Large Sieve and its Applications | series=Cambridge Tracts in Mathematics | publisher=[[Cambridge University Press]] | year=2008 | isbn=978-0-521-88851-6 }} | |||
* {{cite book | title=Introduction to Analytic and Probabilistic Number Theory | first=Gérald | last=Tenenbaum | series=Cambridge studies in advanced mathematics | volume=46 | publisher=Cambridge University Press | year=1995 | isbn=0-521-41261-7 | pages=62–73 }} | |||
[[Category:Sieve theory]] | |||
Revision as of 15:11, 25 October 2013
In mathematics, the large sieve is a method (or family of methods and related ideas) in analytic number theory.
Its name comes from its original application: given a set such that the elements of S are forbidden to lie in a set Ap ⊂ Z/p Z modulo every prime p, how large can S be? Here Ap is thought of as being large, i.e., at least as large as a constant times p; if this is not the case, we speak of a small sieve. (The term "sieve" is seen as alluding to, say, sifting ore for gold: we "sift out" the integers falling in one of the forbidden congruence classes modulo p, and ask ourselves how much is left at the end.)
Development
Large-sieve methods have been developed enough that they are applicable to small-sieve situations as well. By now, something is seen as related to the large sieve not necessarily in terms of whether it related to the kind situation outlined above, but, rather, if it involves one of the two methods of proof traditionally used to yield a large-sieve result:
- An approximate Plancherel inequality. If a set 'S' is ill-distributed modulo p (by virtue, for example, of being excluded from the congruence classes Ap) then the Fourier coefficients of the characteristic function fp of the set S mod p are in average large. These coefficients can be lifted to values of the Fourier transform of the characteristic function f of the set S (i.e., ). By bounding derivatives, we can see that must be large, on average, for all x near rational numbers of the form a/p. Large here means "a relatively large constant times |S|". Since , we get a contradiction with the Plancherel identity unless |S| is small. (In practice, to optimise bounds, people nowadays modify the Plancherel identity into an equality rather than bound derivatives as above.)
- The duality principle. One can prove a strong large-sieve result easily by noting the following basic fact from functional analysis: the norm of a linear operator (i.e., , where A is an operator from a linear space V to a linear space W) equals the norm of its adjoint (i.e., ). This principle itself has come to acquire the name "large sieve" in some of the mathematical literature.
It is also possible to derive the large sieve from majorants in the style of Selberg (see Selberg, Collected Works, vol II, Lectures on sieves).
History
The early history of the large sieve traces back to work of Yu. B. Linnik, in 1941, working on the problem of the least quadratic non-residue. Subsequently Alfréd Rényi worked on it, using probability methods. It was only two decades later, after quite a number of contributions by others, that the large sieve was formulated in a way that was more definitive. This happened in the early 1960s, in independent work of Klaus Roth and Enrico Bombieri. It is also around that time that the connection with the duality principle became better understood.
See also
References
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My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534